Radio frequency identification (RFID) tags are electronic devices that may be affixed to items whose presence is to be detected and/or monitored. The presence of an RFID tag, and therefore the presence of the item to which the tag is affixed, may be checked and monitored by devices known as “readers.” Readers typically transmit radio frequency signals to which the tags respond. Each tag can store a unique identification number. The tags respond to the reader transmitted read signals by providing their identification number, so that they can be identified.
Readers may interfere with each other when attempting to communicate with tags. Interference in RFID reader communications is largely due to an RFID reader operating on the same or proximate frequency (“channel”) as another RFID reader, where the RFID readers are also within an interference range. The interference range may be measured in miles, depending upon the power output of the readers. Interference between RFID readers operating on proximate frequencies and within the interference distance is caused primarily due to a typically large power output associated with RFID readers. Uncoordinated frequency utilization can result in a large amount of interference amongst readers, thereby causing data transmitted by tags to be lost. Lost data requires RFID readers to re-interrogate tags, thereby decreasing throughput. As the number of active RFID readers within the interference range approaches the available number of channels, the amount of interference increases. Due to the increase in interference, the frequency of necessary RFID reader re-transmissions increases, thereby delaying reader throughput.
Therefore, what is needed is a method and system to reduce interference amongst RFID readers when communicating with tags.